Welding Tips and Tricks

Finally got my Everlast 256Si TIG / Stick / Plasma with the water cooler! This thing is pretty awesome! The HF start though on AC is interesting, kinda sounds like a wicked wet fart. ya know the one you run to check your drawers afterwards.
Very pleased with the unit but I'm a n00b so my opinion really doesn't matter yet.
Either way here's some of my results and I'm curious about the aluminum bead closest to the camera. The one in the center I think started out horrible (right to left travel) but then I sped my travel up real quick which you can see where it gets flat and I had a re-grind when I started that one too. I then slowed down just a bit and you can see the final end of that travel with the center bead on the far left side.
The last bead is the closest to the camera and I started out slow but then picked up the pace near the end doing the pause, dip, move technique. I'm thinking this looks good and would be considered an adequate weld but I'd be curious what the experts got to say. I'm not sure how the end of either weld appears since I see what I'd assume is oxides. I paused, added a fair amount of filler, removed the rod, then tapered down the foot pedal for about 1-2 seconds then held for post flow.
The steel looks like I did not have enough Amps for the thickness even when I mashed it too full throttle.
I was running the unit at 100Amps for Aluminum (1/8" thick ) and 90 for the steel (1/2" thick). The aluminum was running probably about 2/3 foot pedal so I'd guess about 60-80 Amps.
You can see the rest of the horror I dished out to this aluminum project box I picked up at Fry's about 8 years ago. That's where I started and what I learned from all this was I was going too slow, had WAY too much Amps with the pedal mashed for most of it, and probably the most valuable lesson I think I've learned so far is tungsten grinding. I did a horrible job at grinding at first where I had an uneven grind all around and even a flat spot for a couple of the re-grinds (lots of re-grinding). When I had the flat spot the arc mostly wanted to arc to the gas cup which was scary. Once I gave it a proper grind with a decent tip, things went much better and that's how I was able to lay some actual beads.
I found the steel to be much more forgiving with the tungsten grinding but still I had horrible results on my other test piece which again was running way too hot and the arc was still not friendly. Once I had a good grind again, it seemed to hold much more what I'd expect it to do, but again I think I didn't have enough heat for the 1/2 thick piece.

I did use my TIG Monster Claws for some of this job especially the last bead and it worked out great IMO. I melted the shit out of my first claw but that's when I was camping out on the spots for way too long with way too much power. Once I figured out a faster travel speed helped out, the TIG Monster Claw held up really well. I've done about 30 minutes under the hood total and so far it seems they're not melting on me any more. This thing is pretty awesome and I'm looking forward to Oscar and Rick's review since I sent them each a set but from the n00b, I'm not sure if I could have made that last bead on the aluminum as nicely as I think it is without the claw. I used Jody's TIG finger for some of the points where I could rest my finger easily and this thing works pretty nicely too. Still, just a n00b but maybe I'll be a true TIGger one day

So in the end I'd be curious to get some criticism on my progress. Be as cruel as you'd like, you won't hurt my feelings

One other question is how often should I be re-grinding tungsten assuming I'm not f'in up? Do I need to re-grind when switching materials and is it more important going from steel to aluminum or from aluminum to steel, or just never/always?

I owe a special thanks to Jody because it's his Youtube videos and other information, along with Mr. Tig and Chucke2009 that gave me the confidence to get started with all this. I did start with stick on my Lincoln AC 225 tombstone but realized I love welding too much to just use that box, and well hell, let's just get into TIG while I'm at it P.S. The Optrel e684 is an amazing hood. I've got 2 others but I don't think I'd be getting anywhere in TIG without this thing.

Not bad..really. Too cold on the mild steel but your doing ok on the aluminum. You have the idea, you just need more seat time and you'll get there.
As far as re-grinding tungsten...Tungsten breaks down as you use it and forms nodules that could cause your arc to wander or become unstable. You won't learn how to weld easily with crapped up tungsten but you will make life easier on yourself if you practice with a fresh grind. After you get your wings, then you will get the feel for welding with a crapped up electrode and you will just deal with it. Sometimes you can dip in steel and keep on going but when you dip in aluminum, you need to stop and regrind as you will not be able to continue. And don't be afraid to crack off the end of your tungsten rather than trying to grind off a dipped mess.
You're gonna F up some tungsten when you're learning but then one day it will all come full circle for you and a pack of tungsten will last you a long time. Part of the learning process and we ALL had to go thru it. Try different grinds and have you will see the differences so don't be afraid to experiment.
There is alot to learn about tig welding but try to ground to your work piece if possible and set yourself up in a good position to weld so you are comfortable, even if it means stacking some metal or wood up so you are in a good position. Thats all I have for now but you will be back asking questions and there are plenty of good welders here that will answer them for you....Good Luck

Entity-Unknown "I was running the unit at 100Amps for Aluminum (1/8" thick ) and 90 for the steel (1/2" thick). The aluminum was running probably about 2/3 foot pedal so I'd guess about 60-80 Amps."

Those amps are really, really low.

1/8" aluminum, 150 amps - more when starting the puddle - it should be formed in 3 seconds or less.
1/8" steel, 125 amps.

Those amps will give you enough heat to pick up travel speed.

Rock on guys! Very helpful and insightful for this hobbyist who'd never get paid to lay beads.
I've been re-grinding almost every run, and I've tried a few different grinding angles. I think I need to start taking a picture of the grind and logging the results in a book or something. I think the tungsten is probably the most important part that we control that a n00b needs to think about before TIGin.
I'll try kickin up the amps a bit and see how it goes but those amp settings for aluminum is what was tearing it up with. I had the worst tungsten grinds then too so it might just be the n00b perception (multiple factors for failure) so I'll give that a try now that I'm gettin at least something that resembles a weld rather than radiation burn.

So two things that were interesting to find out as well... Running without the gas turned on almost destroyed the entire stick out of the tungsten, and created what reminds of of cyanide powder on the inside of the cup, gas lense, and all over the aluminum. Perhaps if you crushed up tylenol, got it all nice n pasty, covered the whole area and let it dry you have the same results I had. Absolutely zero arc control and a complete mess.
The other thing I learned on day one of stick welding and still sticks with me when TIGin is.... your gloves are the last thing you put away! I got an infrared thermometer now so I can check my work area and piece before I grab it. Still gloves should be the last thing your put away even if you need to take em off.

LOL...you will find out right quick if you forget to turn your gas on and you will find out right quick if you forget to hook up your ground clamp. The HF comes looking for you to remind you.
As far as glove go, I have a pair of tig gloves that I try to keep as clean as possible so when I am done with a weld , I take them off and put on my shop gloves OR if I don't put gloves on, I keep a pair of channel locks or pliers on the table to pick up metal if I an going to quench it.
You will know how grind tungsten and you will know how to use an angle grinder AND you will burn yourself many times before you get good at welding We have all been there. Enjoy the learning process because once you get the muscle memory down, it doesn't take a real long time to get good. Have fun and post up more pics if you can.

PS...I lived in Mesa for awhile. I really enjoyed it out there. I hope to move back some day. Used to ride out to Tortilla Flat and Payson alot.

Thanks nailpounder! Guessing an ex-iron worker? When the girl's leg isn't broken from being crushed between a bumper and the swing arm we're definitely hittin the roads again! I ride a bit still but I feel bad for her so I keep it at a minimum. It's also deep in the summer so it's an easy excuse for now....
I tried Tortilla Flats a few months ago and that was a horrible idea for my CBR600 F2. I almost wrecked in the first corner because the road has a 2-6" ripple every few feet that beat the crap out of my suspension and me. That first corner had decent asphalt leading into a blind corner where the wicked ripples begin so I had a comfy speed but hit that and the front wheel lifted up and to the left.... Yes I checked my drawers after! I went about 1/4 mile and had to call it a day. Probably one of the only moments in life I wished I had a Goldwing
I've got quite a few runs laid out for the state that have been awesome rides. My favorite so far is goin up to Wickenburg/Congress area, through Jerome and cutting up to Sedona/Flagstaff. Amazingly wicked corners that'll keep you on your toes the whole way through.
I've gotten the heat quite a few times. That was weld #1 with the stick after grabbing the part with my bare hands. F'in idiot! Instant reminder and hard to forget that one Jody's TIG finger has been helpful but I'm still learning how to use that too. I've got some BSX black gloves with the short cuff that I'm liking because of the dexterity. The long cuffed BSX gloves I have I'm not too fond of. $20 vs $40 I guess...

I do keep my vice grips and I got a set of C-clamp vice grips within reach. I got a generally comfortable setup too. One of the best things I did for comfort was hanging a bungee cord off my cabinet door and attaching it mid way in the cable. I've got a #18 water cooled torch that is VERY heavy in the sense of hand tools and it's awkward with the cable wanting to pull the torch up away from the work thanks to our friend gravity. The bungee took all the weight off so now I can hold this thing steady.

Here's a pic of my work area which will one day have my welding table I've got done up in CAD. It's foldable and will only take up about 1' x 4' of garage space when folded. I designed it so it can raise and lower using 18" receiver tube. I'll post some pix of the CAD soon.

In the mean time here's where I get to work

One day when I know WTF I'm doing I'll be stick'in this table together. The general bill is looking about $800 for the steel to build. Haven't decided yet on C-stock or tubing for the top yet but I think C-channel will be the winner. TBD!

I'm a Harley rider but we can still be friends. I used to roadrace back in the 80's so I wasn't always a snob You would be suprised how I can make a Harley corner. I have hung in some corners with some young guys on crotch rockets and gotten some High 5's...probably for not bothering to wear a helmet and no sleeves
Are those Neil's Garage Cabinets in your garage? I worked for them when I was out there.
You will be alot more comfortable with a good table. You don't need to go crazy on cost to get a good one either. Other than that you just need seat time. Jody's vids are awesome and I still go back and watch them because there is always something I pick up that I missed the first time. I got back into tig about 2 years ago after a 15 year layoff and even though I sorta remembered how to tig, Jody's vids got me up and running in a few weeks and now I am very cofident again but I wish I got more tig work . I have a stainless job tomorrow that I am pretty excited about but other than that its mundane mig all the time. You're gonna have a lot of fun and even more fun that hobby welding is when you start making money at it.

Ha I'd never completely judge a rider by their choice of ride. It's just choice of riding style really. I like zippy and I like to lay down so the rocket is for me. As for cornering, 99% aren't even capable of pushing their machines to the max. Most cornering fails and limitations are simply rider so 99% of the time it doesn't matter what you ride, just matters if you know how to ride it

I checked the cabinets and they say Premieregarage.com so I'm guessing they're not Neil unless that's an installer. They came with the house but I'm glad they did. I've got em pretty well filled and couldn't be happier with the quality. I feel spoiled with this home especially the garage. Even has a wash sink which'll make any girl happy

I love Jody's videos and his personality fits mine better than Mr. Tig or Chucke ableit those guys are very helpful too. I've watched most of their lesson style videos numerous times and I know even if I can hit pro level, I'd still likely reference them because as you called it, they'll be good reminders especially when TIGin isn't your 8 hour profession. Even if it was I'm confident they'd still be useful.

I'm a security engineer so I develop security technologies and I take existing technologies and build them out to get the job done. I've got 16+ paid years experience with 27 years of hands on work backing me there. I'm one of the best in the world when it comes to web application firewall design, I even have a patent pending rate limiter/brute force detection tool I developed. Even when it comes to the stuff I know inside and out, I still google the crap out of things. My favorite acronym is RTFM and it's never let me down! GIYF is my other go to acronym. I really enjoy my work but I really don't use computers much outside of the work place. Fortunately I have a fun job and get to do whatever I want really, but I try to keep hobbies like welding for 100% enjoyment rather than a paycheck so I don't ever suck the fun out of it being forced to do things the way someone else wants me to do it.

The only thing I might make some money off of one day for welding is when I build my girl and my turn tables for our bikes. I've got a 6 car garage but that lil runway with the bikes doesn't make it easy to spin a bike around and no one enjoys a 20 point turn. Backing out is easy BUT who wants to do that if you've got the skills (gettin there) to build up a turn table to spin the bike around in place? If I do well enough I'm sure I'd have a few requests but even then it wouldn't be a living. Just funding more supplies if anything.

If you ever come back to Maricopa county, we'll always be down for a bike ride. It's our lives and it's hard to imagine life without two wheels. Layin down beads n rubber.... Can't get much better

So a bit more practice before I run out of gas and before I called it a day. Time to hang out with my true love. I think I'm progressing pretty well for a beginner but I've got a long ripply road ahead of me with hopefully the least amount of bird turds running along that beaded path.
You all are awesome and I appreciate the insight. I wouldn't be able to have gotten this far without the educational videos and reading all the posts I have before I got started. I'm kinda sad I didn't get into this sooner but I've got many years of happy welding ahead of me. Can't wait to be a true TIGger

You need WAY more amps for 1/2" steel than what you are using thats why your weld is so cold. You want to form a puddle instantly and later on when you do stainless and thicker aluminum, you will know why. Remember Jody's rule...1 amp for every 1/1000th. Up to .125 the rule works pretty good and after that it is just a guideline. You should be using around 250 amps for 1/2" steel. I do that thickness with less amps but I bevel the metal and do a root and hot pass. You really need alot of amps for aluminum as it conducts heat so fast. Also I assume you are using 3/32" tungsten? 250 amps is way too much amps for that size electrode. You would be better using 1/8". Get thinner steel if you can and follow the rule. I usually go 10 or 15 amps above the rule and just use the pedal to control the amps. try to stay with smaller amperages and get used to feathering the pedal before you move onto thick stuff.
You will be a true tigger before you know it. One day it will just click and then you will be all cocky and shit
Neils garage cabinets is a company I worked for when I lived there. They are/were out of Chandler or Gilbert or something like that.
I hear you on the cornering thing. Lots of guys loose their nerve in the curve. Hell I regularly drag my floorboards on my Street Glide with my wife on the back. She's alot braver than most I would never ride with someone that drives like me!
Cool career you have...I know very little about computers and I kinda like it that way. I save all my remaining brain cells for gun knowledge. So anyway..keep us informed and updated on yor progress. There are many good welders that come through here and they all have a tip or 2 for the new guys. Thats what is so cool about this site...no attitudes and everyone bends over backwards to help others. I'll be talkin to ya...

You called the 3/32 tungsten nailer! I bumped it to 150 for the steel and it doesn't look as pretty, very dull. I do have thinner steel. My local metal shop, AZ metals sells variety packs for $20 for the curious welder in mind. They even divvy them out in a way that suits your n00b needs such as more round stock over flat/square stock but still give you a mix of both. So I do have a variety of pieces to work with, I just got comfy with the 1/2 stock from when I started stickin. Lots of "stick"in.... I'm thinkin I got more than enough Amps because if I hold too long say from the hose getting caught up or me suckin at feeding, I burn through. I also noticed I have 14/16 gauge aluminum not 1/8 so I'm certain the Amps won't be at 250 but that's my fault for telling a bad story.
Feathering gave me some interesting results and perked a lot of ideas. I've got sewing experience so the pedal makes some sense with controlling the arc. I think my tungsten grind angles is still playing the biggest part in my quality of welds beyond operator control. I never thought it'd be so important but I'm thinking of all things to be concerned about, the grinding might be the most important. Am I wrong?

Sounds like you and the girl got it made! Just need to get her off the back and on her own two wheels Life is about comfort so don't worry I'd never judge what seat someone was in but I will always respect someone that knows the "freedom" of two wheels. I was always told it since my Mom rides a rocket and worked with a bunch of bikers but I never truly understood what they meant by "freedom" until I took that first corner. I was sold instantly

As for the career, I love my job. It's too perfect and I'd never trade it if I could. There's something special about shuttin down hackers, even if you've got your own criminal history. Logistics, intellect, relative experience, and a knack for seeing the difference between a true right and wrong

So my real questions I have left with any criticism someone's willing to dish out.....
Is there a theory behind ambient temperature such as 106 degrees Fahrenheit being cause to adjust say 10- Amps? That's a random figure but I think a reasonable guess...????

Is the stickout and grind angle I posted before about what I'd want with an inverter and running 1/2 or less steel/aluminum? I've had a variety of qualities in my welds but haven't had enough experience to observe what's been working and what hasn't.

With my progression, from a professional stand point would I be capable of making an aluminum fire prop that can handle kerosene/white gas flames and be functionally stable? Or do I have a long ripply road ahead before I could even think of that?

Lastly, I posted a pic from my Everlast manual regarding tungsten grinding. From the n00b to the n00bs that might be reading this, I think this is very important and Everlast did a wonderful job of explaining the procedure.

How thick is your filler rod? If it's too thick that may be part of the reason your beads look like there sitting on top of the base metal.

What are your welding parameters? What type of tungsten are you using? The grind of your tungsten is important but not as much as torch angle and arc length etc...There are several things that all need to mesh to get a good weld. Jody has an excellent video about the 3 most common things that people do wrong when tig welding. I am too lazy to post the link because I want you to research his videos and watch them all.
IMHO...and I think others would agree, you should not be attempting do weld aluminum at this stage in your learning. Aluminum isn't hard to weld it is just different because when things go bad on aluminum, they go bad really quick so I recommend staying with thinner steel for right now so that you get your muscle memory and timing and pedal control and all the other things you need to be good at to turn out good welds. Don't try to run before you can walk, so to speak.
You can see in the last pic how the metal has just melted away. That is because the heat has nowhere to go and builds up and the metal just drops out. You need to be good on the pedal to weld aluminum and that is a skill that takes some time to develope.
None of us here invented tig welding and none of us were born with the natural ability to tig weld...ALL of us had to learn and advancing in the learning process requires progressive steps from beginning to mastery.
Ok...now that I beat you up a little bit ..get some thin steel and start there. Don't go for the big amps yet because big amps means more heat you are pouring into your base metal and more things will go wrong. First we crawl, then we walk.
Like most, you want to get good at welding and that is commendable but it just takes time and if you afford yourself that time you will progress faster than if you keep having to unlearn mistakes. All the bells and whistles on todays machines will NEVER replace the basic skills that the "torch nut"(the weldor) has to acquire to be competent at his craft.

exnailpounder wrote: All the bells and whistles on todays machines will NEVER replace the basic skills that the "torch nut"(the weldor) has to acquire to be competent at his craft.

Well said, +1

Thanks guys! I promise I've got at least 30+ hours of pure Youtube time not including all the research. If there's a video about basics, common mistakes, how to, beginners, aluminum, steel, stainless steel, I've watched it from Jody and the other guys out there which I've watched several times over and will still continue to watch even after I think I got it right Oh yeah Jody's Aluminum welding drill is probably the best yet, straight to the point, and I've watched that at least 5 or 6 times too! I've got tons of notes I've taken so I've got about at least 2 straight weeks of total time before I ever turned the machine on. I'm good at research and I'm far from done

I think it's all the research and the little play time I've had that's helped me read my welds. I've certainly gained from ya'lls replies here too.

So for the thickness, the aluminum is actually 16 gauge once I measured it finally. The filler rod I'm using is all 3/32 4043 for Aluminum and ER70S2 for the mild steel. The amps were 100 for aluminum with about 1/2 to full pedal depending on what I was practicing and what I was feeling out. Same story for steel except 120 Amps for that almost 1/2" thick piece.

I can actually say that hole in the latest were actually from the first rounds I did when I was destroying everything. I just keep using the same piece and try to work around that hole till I feel I'm ready to try filling in that hole with a copper backing plate. The last welding run in those pics had no burn throughs and the edges that were melted were almost all from the original runs but I think I had a couple points where I toasted the edges up a bit with that real small piece. So there really was improvement! I'm seeing the benefit of cleaning the part up after a bunch of bad runs too but that was part of what I wanted to see would happen.

I'm really liking doing the work on steel. I've got a license plate the MVD tells me I must destroy which I think is stainless steel...Maybe? I'm gonna clean that off and destroy it for them. Hopefully it's stainless but I guess I'll find out when I start adding filler.

When I grinded the tungsten with the bottom of the arbor like what the Everlast manual says not to do, I had the worst arc control with the arc all over the place and all I got was the radiation burns. Once I grinded it right, I haven't changed much and I've at least melted metal rather than burn the crap out of it all over the place.

As for all those fancy bells n whistles... I'm afraid to touch them for now. Tempted to turn on that pulse just to prove a point of pedal control to myself but I refuse for now. I'm liking the 100% manual process which is just how I generally like to do most work as is.

I'll definitely practice more with the steel since I agree I'm finding more simplicty and consistency when trying to learn things. I've also learned it's really important to let things cool down a bit before I keep doing runs, otherwise I'd say the part is getting too hot and since I'm keeping the same Amps, I'm just tearin stuff up or easily dumping too much filler in to keep that bead a bead. When I first start and have a good pause between runs, I'm finding things to be more consistent until I get hasty then everything shows I was hasty.

I think I'm gettin the hang of it but still have a long way to go and at this point need some fresh pieces of metal to work with but I'll still keep stacking the beads on these pieces as I clean them up too

The "research" will make a lot more sense after your first 100 hours of actual practice.

MinnesotaDave wrote:The "research" will make a lot more sense after your first 100 hours of actual practice.

+1.

I am now on my fourth bottle of argon - each one larger than the last - and the practise I've accumulated together with endless hours of watching Jody's videos means I am finally, in my own humble way, starting to see things come together.


Kym

As stated above, it will take you about 100 hours to get the muscle memory and knowledge you will need to light up with confidence. With confidence I mean welding any metal that's put in front of you. I doubt that your lisence plate is stainless but it could be 400 series stainless, Check it with a magnet. You can weld stainless with mild steel rod, it's just not going to be stainless in the weld area anymore but it will hold. Welding stainless requires some extra steps because stainless doesn't conduct heat worth a damn and it warps and blows out and does all kinds of crazy stuff if you don't take precautions. It does weld really nice and is my favorite metal to weld but you have to know about it's conductivity properties before you work on it. In addition to being a weldor, you also need to be somewhat of a basic metallurgist as different metals have unique properties and that can/will affect how its welded. No doubt you have seen the differences between mild steel and aluminum. Thats why I recommend starting with mild steel as it is the most forgiving and the cheapest and get your movements and timing down before you move on to conquer more difficult metals. I won't even mention that you can bond dis-similar metals with your machine(oops I just did) with brazing rod but thats a whole different topic and a little more advanced skill. I have been a life-long learner and I think learning is fun so I always tell new guys to enjoy the process of getting another feather in your cap. Keep sending pics!

Yeah the two weeks of research for Stick before I started that then the two weeks of research for TIG before I started that I know just by looking at my welds is only so useful. It's all theory until you can show it in practice. Fortunately I have a pretty damn good memory so most of the things are lingering but even when I'm thinking about it doesn't mean I'm doing it i.e. that muscle memory...
I'd like to think I was smart and purchased 10Lbs of 309L, 308L, 5636, 4043, 4943, 70s2, and now I'm thinking I just realized I forgot to order the silicon bronze... I've also got 1Lbs extra of 4043 and 70s2. Basically I wanted to make sure I can play and do anything I want AND I always wanted to purchase everything now since I'd imagine as time goes on, filler rod will always go up in price. From all my research these were all the rod types that I'd ever need for the rest of my TIG life. I'll only be playing with 4043 and 70s2 for now and maybe some of that 308 for the license plate to see how that works out. The rest will be for when I hit that point where I can say I can pick up a torch, lay a bead, make a joint, and I don't see anything wrong with it. I won't be a welder then either, just capable

Just upgraded that lil pony 20CF bottle to a 50 too. I gather the inevitable truth is you will always run out of Argon on Sat after noon...... I figure the 50 will last me a bit longer simply because I'll have less stop/restarts than I started with but I'm sure it'll only travel so far too. Seems like 50 would be best for me since anything bigger has a potential for having some wasted gas left in the tank as is just taking remaining cubic volume / pressure math into account.

I'll add some more pics of maybe that license plate when I start up on that and some more fresh pieces so it'll be more worthwhile of making distinctions of whether I'm not progressing rather looking at mediocre learning piled on top of absolute shit

One other tip I mentioned else where that I recently learned and have yet to have ever hear any suggestions for....
Secure your pedal!
I've got a coated garage floor so it's smooth and that pedal ran away from me a couple times. Immediately everything that can go wrong, did. I dipped, moved, long/short arc'd, lost my path, squirmed, and yeah, just ruined that run and had a lot of fixin to do afterwards. Welcome to manual pulse/feathering the pedal I thought....
I'm thinkin some of those non-skid pads on the bottom of my pedal will be a wise investment.

If you have an old car floor mat to put your pedal on, it helps. Sounds like your set up with filler rod. If you don't mind me asking , what do you pay to get a 50cf bottle filled out there? I just filled my 330cf for $70. Reason I asked is because it is far more economical to utilize bigger bottles, especially when you are starting out and burning up some gas. Those big bottles last a long time. Sometimes you can find bottles on Craigslist for sale. There is no real benefit to owning over leasing or renting but when your lease is up after 7 years, you still get to keep the bottle.

Yeah I'd never rent either. I don't like owing and I hate bills. Hmmm I think it's a 60CF. I thought they said 50CF but whatever.

So I got a $75 credit on my 20CF and the purchase of the 60CF at $100 put me at $25 there.
The "fill" cost $26.52.
So I walked out with that exchange for $56.76 in the end. I think around $70 is what she said for the biggest tank they'd give me.
After watching the gauge drop I might take your idea into consideration. Fortunately it seems like the trade up process is gonna be pretty economical as well. Harbor Freight sells bottles for $100 and with a 20% off coupon you can go do your normal exchange but it's a 20CF. If I went to the AZ Welding Supply Store here in AZ, the HF option would have been cheaper because it was like $120 for a 20CF and fill with an over the phone quote, not in person. I went to Vern & Lewis and I can now see I shoulda just talked to them in the first place and would have paid the same for HF 20CF bottle as I would have for a full 60CF bottle with no exchange at Vern & Lewis.

I'll have to get past my OCD to use my floor mat that I've pulled out of the Outback....

Well that license experiment with some 308 would have been fun.... I included a snippet below explaining exactly what a license plate is made from. I think I'm just going to assume I don't know that and try the 308 out anyways. Doesn't hurt to learn first hand what a metalurgist will need to know when mixing incompatible metals

The raw materials used to make license plates include sheets of aluminum, preprinted and colored reflective and adhesive sheeting, and paint. The aluminum blanks are usually precut to size by metal manufacturers and supplied in this form to correctional institutions or other plate makers.

Another vote for big tanks. I use a 330 cu.ft. tank mostly. My spare is a 150 cu.ft.

Note: if your flow meter is set at 16 cfh, then a 20 cu.ft tank gets you about an hour including pre/post flow.

Pretty hard to get your first 100 hours of practice like that.

Go big.